Scatter correction for camera based coincidence and single photon imaging protocols

We have investigated and tested a strategy for acquiring projection data fr om a mixed field of a positron emitter, a single photon source, and a trans mission source, and independently reconstructing each of the three data set s. Tc-99m is imaged through the collimator using conventional SPECT techniq ues. The annihilation and the transmission radiations are detected as they penetrate (uncollimated) through the collimator septa. The success of independently reconstructing each data set rests on the effe ctiveness of the scatter subtraction method. A few scatter compensation met hods were tested. A scatter compensation algorithm (based on 3 energy windo ws) within an iterative reconstruction algorithm was applied and quantitati ve improvements of the emission reconstructions are reported. Our experimen tal results of immediately sequential Tc-99m, FDG, and I-131 transmission d ata, demonstrate that each isotope can be imaged in the presence of the oth ers. This method could be extended to truly simultaneous acquisitions.